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Expert amateurs: local dive guides report sharks for citizen science

Which of these two groups do you think would know the whereabouts of sharks better: local dive guides or professional marine biologists?

In a new paper in PLoS ONE, marine researchers in Australia report on the reliability of data collected by experienced SCUBA divers. Can amateurs report observations of sharks accurately?

The researcher did not actually compare observations of experienced SCUBA divers to professional observations. That answer will remain debatable. The researchers compared relative abundance of sharks estimated by dive guides to estimates by passive acoustic tagging and telemetry. They used data from 62 dive guides during over 2,000 dives on coral reefs in Palau, Micronesia for 5 years. Dive guides reporting on the dive site, date, species, counts, estimated depth, current, visibility, and number of tourist divers in the group.

Time and again, when leisure and science intersect, we gain new knowledge. There is a long history in some disciplines, like astronomy and ornithology. During the Victorian era, large-scale citizen science advanced understanding of the ocean and tidal environments. And yet, to this day doubts apparently remain as to its efficacy.

I’m talking about enthusiasts who enjoy observing the natural world, and frequently they become experts at observing it. Their observations can be useful for scientific goals when used appropriately.

Photo credit: Frank Gibson

In this context, researchers can stop asking the question, ‘can citizen scientists collect reliable data?’ Citizen science volunteers have repeatedly proven to be reliable, careful, and enthusiastic (and probably better than your novice undergraduate intern). The reasonable questions to ask are the same as for any field study, such as: ‘what data collection protocol works best?’, ‘how can we deal with sampling biases?’, and ‘how can we obtain the necessary sample sizes?’

This is not to trivialize the assessment of methods for citizen science. If recreational divers do not follow rigorous protocols, their observations may not be useful due to rounding bias, inflation bias, or misidentifications.

There are over 1,000 species of elasmobranchs (sharks and rays), and there is not enough information on almost half of those to assess their extinction risk. The lack of information on so many species prompted the desire of researchers to fill these data gaps with observations by dive guides. Sharks are important to the structure and function of the marine ecosystem. They have naturally low population densities and large home ranges that can span the coasts of multiple countries. In the current study, the estimates from recreational divers matched those estimated from data derived from passive acoustic telemetry of tagged individuals. Furthermore, based on telemetry data, the researchers showed that divers do not inadvertently influence a shark’s relative abundance and depth. This finding reinforced the general notion that sharks easily acclimate to people (not a comforting thought).

Ultimately, the authors trust the divers. When they carry out an analysis of possible environmental variables that might influence shark distribution, they used the citizen science data, not the telemetry data. They find water temperature and strength of the current influenced shark abundance.

Even though the study was prompted by the need for proof-of-concept that divers could fill data gaps for assessing extinction risk of all shark species, citizen science may not meet this goal. Even with expertise in gathering correct information about sharks, if a study is not designed to effectively address its research goals, then it won’t achieve those goals. Observations of sharks by divers, no matter how accurate, that are “from a few popular dive spots may be useful for local management measures, but it isn’t the sort of data that can help change an IUCN Red List status from Data Deficient,” says David Shiffman, a shark researcher (and Ph.D. candidate) at the University of Miami’s Abess Center for Ecosystem Science and Policy. Many of the poorly understood species live in the open ocean, not in areas with divers.

In a press release, the lead author, Gabriel Vianna, said, “Our study shows that with a little bit of training and a good sampling design, recreational divers collect very useful data that can be used to monitor shark populations over long periods of time and across large spatial areas. Such programs have relatively small costs when compared with other methods currently used.”

We can look at the cumulative research about and by citizen science and impose some minor edits to make a more sweeping conclusion: with a little bit of training and a good sampling design, recreationists (citizen science volunteers) collect very useful data that can be used to monitor shark populations over long periods of time and across large spatial areas. Such programs have relatively small costs when compared with other methods currently used.

Citizen science design allows scientific practices to benefit from the expertise of amateurs.

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Caren is an Associate Professor at North Carolina State University, Chancellor's Faculty Excellence Program in Leadership in Public Science, as well as the assistant director of the Biodiversity Research Lab at the North Carolina Museum of Natural Sciences. She is an avian ecologist and relies on citizen science to help communities use birds as indicators of environmental health. She hosts monthly chat sessions about citizen science on Twitter. Follow her at @CoopSciScoop

Recreational divers play a major part in the collection of useful data that experts use in monitoring shark behaviors and populations. With proper training, they can become a more vital asset in the preservation of these wonderful creations that have faced extinction time and time again because of the greediness of humans.